The industrial fields of cosmetics, catalysts, electronic materials, battery materials, fine ceramics, pharmaceuticals, and foods involve production of particles, in particular, fine particles.
In general, two or more reactants are fed in a stirred reactor equipped with a stirrer, the reactants are mixed in a liquid to prepare the liquid containing a reaction product (produced particles), and the reaction product (produced particles) is separated from the liquid. A typical example of this process is disclosed in Patent Literature 1.
Unfortunately, in the production of particles in this stirred reactor, the diffusion of the solution of the reactants is the rate-determining factor, causing local reaction to readily give crystals irregular in size and shape. In addition, preparation of fine particles needs to increase the rotation speed of the stirring blade, which requires high power and is not economical.
Patent Literature 2 discloses an apparatus for producing sodium hypochlorite. This apparatus generates a spiral flow in a cylindrical shaped vertical reactor by inflow of a circulating reaction liquid into the vertical reactor in the tangential direction, and chlorine gas is fed from below the spiral flow to be brought into contact with an aqueous sodium hydroxide liquid.
Although the reactor of Patent Literature 2 has an advantage of a high contact efficiency of the chlorine gas by virtue of the spiral flow, the contact efficiency to the target only by the spiral flow is not sufficient.
Further, the present inventors have proposed a crystallizer that can produce crystals improved in uniformity of the size and shape as shown in Patent Literature 3 and have verified the advantages. However, the inventors have found that this crystallizer exhibited a limited improvement because it used only a spiral flow.